Electrophotographic apparatus



March 7, 1967 F. HUNSTIGER ET AL 3,307,458

ELECTROVPHOTOGRAPHIC APPARATUS 3 Sheets-Sheet 1 Filed June 4, 1964 l l II w w m wmm mso N w T Bm ms mm FHW I ATTORNEYS March 7, 1967 F.HUNSTIGER ET AL 3,307,458

ELECTROPHOTOGRAPHIC APPARATUS Filed June ,4, 1964 s Sheets-Sheet 2 FIG-486d 7 I I 86c lllllllllllllllll 51 93 INVENTORS a! FRANCIS HUNSTIGER a 2RT E. DRAKE ATTORNEYS March 7, 19,67

F- HUNSTIG ER ETAL ELECTROPHOTOGRAPHIC APPARATUS 5 Sheets-Sheet 5 FiledJune 4, 1964 ATTORNEYS United States Patent 3,307,458ELECTROPHOTOGRAPHIC APPARATUS Francis Hunstiger, Parma Heights, andHerbert E. Drake,

Willowick, Ohio, assignors to Harris-Intertype Corporation, Cleveland,Ohio, a coporation of Delaware Filed June 4, 1964, Ser. No. 372,503 14Claims. (Cl. 951.7)

This invention relates to an electrophotographic apparatus and moreparticularly to an improved electrophotographic system for forming aseries of images and especially multi-colored images on anelectrophotographic member.

In conventional printing systems, for example, multicolor lithographicor letterpress printing machines, the process usually involves themaking of printing plates by any of several well known techniques, andthe plates are thereafter assembled on the press. Each of the stationsrepresentative of the several colors constituting the multicolor imagerequires a plate representative of the image to be printed in aparticular color, and after all of the plates have been prepared, theyare assembled on the machine and the plates are secured in registeredposition to provide a composite multi-colored printed image with theseveral images being in registry. The registration procedure for thistype equipment generally includes printing test copies, making anynecessary adjustments of the plates, and repeating these operations asmany times as may be required to bring the plates into proper registry.Additionally, the cylinders about which the plates are secured are of afixed diameter and thus in the case of web fed equipment, presentpractical limitations on the size of images that may be printed withoutundesirable waste of the web between images.

These procedures represent conventional practices in the printingindustry and one of the disadvantages is that the set-up time isextensive, for example, from one-half hour to six hours or moredepending on the number of colors and the complexity of the equipmentinvolved.

The present invention relates to multi-color printing equipment whicheliminates pressure contact between the members which form the printedimage. The apparatus in accordance with the present invention makes useof transparencies in the form of color separation units each of which isrepresentative of one of the colors constituting the composite colorsubject. The set-up time for the apparatus of the present invention issubstantially less than that of lithographic and letterpress equipmentpreviously described. Additionally, there is the advantage that maximumweb utilization is possible since the length of the image is notdependent upon the fixed diameter of a printing roll, but the imagelength may be varied within substantial limits and successive images maybe spaced any desired distance apart along the web. Further, theequipment itself is substantially lighter in weight than letterpress andoff-set equipment, and requires less cleanup time.

Accordingly, it is an object of the present invention to provideeletcrophotographic apparatus capable of producing images properlyregistered with respect to a web of electrophotographic material passingthrough the apparatus, which apparatus requires no pressure contactbetween the image forming elements.

It is a further object of the present invention to provideelectrophotographic apparatus capable of producing images representativeof different colors, or portions of a composite subject, which imagesare properly registered with each other.

Another object of the present invention is the provision of an improvedweb fed electrophotographic apparatus usable in multi-color reproductionsystems wherein the web and projection system are so arranged anddisposed that there is initially proper registration of an image on theweb, and all subsequent images are registered with reference to thefirst image.

Another object of the present invention is the provision of an improvedprojector and registering system for lateral alignment of an opticalimage on a moving electrophoto graphic member.

Other objects and advantages of the present invention will be apparentfrom the following description, the accompanying drawings and theappended claims.

In the drawings:

FIG. 1 is a schematic view of the multi-colored electrophotographicprinting equipment in .accordance with the present invention;

FIG. 2 is a schematic view of the relative position of the switcheswhich are adjustable to coordinate severance of the web in conjunctionwith the image formation thereon;

FIG. 3 is an enlarged detail view of the projector shown schematicallyat the first station in FIG. 1;

FIG. 4 is an enlarged fragmentary view of a portion of the projector asseen from the right of FIG. 3;

FIG. 5 is a plan view of the film holder and mounting assembly therefor;

FIG. 6 is a view from the left of FIG. 5 of the film holder and mountingassembly;

FIG. 7 is a view partly in section and partly in elevation along thelines 77 of FIG. 5;

FIG. 8 is a view of the projector and web position sensing assembly ofthe present invention as viewed from the right of the first stationshown in FIG. 1;

FIG. 9 is an enlarged view partly in section and partly in elevation ofthe mounting between the pivot lever arm and pivot support of the webposition sensing device in accordance with the present invention; and

FIG. 10 is an enlarged fragmentary view illustrating the relativeposition of the sensing arm with respect to the position of the web.

Referring to the drawings, which illustrate a preferred embodiment ofthe present invention, the electrophotographic apparatus 10 includes aplurality of stations 1211, b, c, d and e, and each station includes acharger 14a through 6, a projection unit 15a through e, and a developingunit 16a through e. For simplicity of illustration, the projection unithas only been shown in the first station 12a. The various components ofeach station are assembled and secured to frame elements not shown whichsupport these individual components in their proper relationship. A rollof electrophotographic paper 18 is supported by the frames for rotationas indicated, and the web is fed along a path of advancement whichincludes guide roll 19, over a guide roll and dampening assembly 21through the first charger 14a and over a freely rotatable guide roll 22.The guide roll and dampening assembly 21 includes a freely rotatableguide roll 23 which rotates in contact with. a dampening roll 24 whichis partly submerged in a trough of water 26 so that a relatively thinfilm of water off-sets on the guide roll 23 and is transferred to oneside of the electrophotographic web 30. The other side 32 of theelectrophotographic web is positioned to be charged, exposed anddeveloped seriatim as will be described more fully hereinbelow.

After passing over guide roll 22, the web passes across the lower faceof the projection table 34 which defines the image plane where it isexposed to form an electrostatic latent image having a chargeconfiguration representative of the first color to be deposited. Duringthis exposure operation an index mark is also placed along one edge ofthe web in predetermined relation to the latent image. The exposure ofthe web in the first and subseprojected images in longitudinalregistration with the first first station.

From the projection table 34, the web is advanced over 'freely'rotatableroll 36 with the exposed surface in contact with the roll and into thedeveloping station 16a which includes a web driven developing drum 37awhich is positioned transversely of the web in a tank 38a containingliquid developer of the type described in application Serial No.762,756, filed September 23, 1958.

Positioned in pressure contact with the web 30 on the upturning side ofthe drum 37a is a squeegee roller 39a, and the axis of roll 39a ispositioned with reference to the axis of developing drum 37a so as toform a pressure nip therebetween to effect removal of the carrier liquidof the liquid developer. The web is preferably maintained in intimatecontact with the outer periphery of the developing drum 37a to preventwetting the reverse side of theweb with developer carrier and to preventdeposit of toner on the reverse side of the web.

The remaining stations 1211, c, d and e include basically the samecomponents described in connection with the first station 12a with theexception that wiper mechanisms 41b and 42b are associated with guiderolls 22b and 36b, respectively and similar wiper mechanisms areprovided for the remaining stations. Guide rolls 2211 through e andguide rolls 36b through include an outer covering whose surfacecharacteristics minimize transfer of the deposited developer to theroller for example such as polytetrafluoroethylene from which anyoff-set material may be easily removed by the respective wiperassemblies 4112 through e and 42b through e which may be periodicallyrotated to provide a clean wiping surface as needed. Alternately, rolls22]) through 2 and 3612 through 2 may be wetted with water to preventoffsetting of the developer since the toner is dispersed in ahydrocarbon vehicle which does not mix readily with water.

From the last station 126, the web moves over a freely rotatable guideroll 44 and through a dryer (not shown) and through driving pinch rolls45, and to a sheeter assembly shown schematically-at 50'. For thedetails of the sheeter mechanism, reference is made to applicationSerial No. 241,423, filed November 30, 1962, now Patent No. 3,223,008,and assigned to the same assignee as this application.

The web is maintained under relatively constant tension during travelthrough the various stations by suitable Web tensioning devices, forexample, of the type described in Serial No. 241,423 previously referredto. Associated with one of the stations is a triggering device which isactuated by movement of the web to cause triggering of the flash circuitof the projector in the first station and which also includes a secondswitch for controlling the sheeter assembly 50.

Referring to FIG. 2, associated with one of the rolls 22b through 6 or36!) through e or with a separate roll arranged to be driven by the webis a gear train 52 including gears 53 and 54 which may be changed toform different ratios which determine the length of web per image. Bychanging the ratio between gears 53 and 54 various lengths of web may beestablished with reference to the image size so as to provide arelatively small web length between successive images in series.Associated with gear 54 are two cams 55 and 56 which are adjustablymounted to gear 54, cam 55 operating to actuate a switch 57 forproviding a trigger pulse for the flash tube in the projector of thefirst station, and switch 59 which is tripped by cam 56 to actuate thesheeter assembly 50. Switch 59 is affixed on a support member 60 whichis mounted for rotational adjustment about the axis of gear 54 therebypermitting adjustment for severance of the web between two images alongthe length of web during operation of the machine. By adjusting cams 55and 56, and adjusting switch 59 through movement of supporting member 60and by changing gears 53 and 54 to different ratios the web travel andthe severance of the web may be so coordinated that a series of imagesof a given length may be cut in sequence from the web and thereafter aseries of images of different length may be made and the web cut toproper lengths.

Atfixed to the frame, not shown, is a stationary slide assembly 66,movement of slide assembly being controlled by a micrometer screw knob67. Turning of the micrometer screw knob 67 effects movement of a slideelement'69 and thus the entire projector assembly generally designated70 is moved towards or away from the corresponding projection table. Thevprojector assembly 70 is fixed to the slide member 69 by a supportingbase 71 which also forms a fixed support member for a pivotal arm usedto sense the position of the web as will be described more fullyhereinbelow.

The projector assembly 70 includes a cover73 which houses a flash tube,a trigger transformer, a mirror and condensing lenses, not shown. Cableconnection 74 receives acable supplying the trigger pulse to fire theflash tube, and cable connectors 76 and 77 supply the power to the flashtube itself. Member 80 is fixed to the supporting base 71 and provides asupport for the film holder assembly, generally designated 85. As shown,flexure plates 86a and 86b, and a second pair of flexure plates 86c and86d positioned in spaced relationshipthereto are fixed at one end tomember 80 so that the pairs of plates 86a and d, and 86b and 0 permitslight lateral movement of a lens and holder assembly 87 mounted on theother end thereof. To the upper portion of the fiexure plates is fixed asupport member 88 which is provided with an internally threaded apertureto receive an externally threaded lenshousing 89 to which is aflixed alens 90. The lens 90 includes an adjustable aperture and an objectivelens, not shown, and the aperture of the lens 90 may be adjusted in theconventional manner by turning rotatable ring 92 relative to the lens90.

Referring to FIGS. 5 through 7, mounted on member 80 are a pair ofspaced guides 93 and 94, guide 93 being fixed relative to member 80while guide 94 is mounted for movement around pivot 95. Guide .94includes a shoulder 96 running the length thereof to provide a track andreference edge for the filrn holder 85. Mounted on guide 93 is a leafspring assembly 101 which urges the film holder 85 toward guide 94 andagainst the shoulder 96 while a second spring assembly 103 forces oneside of the film holder 85 into contact with the upper surface of guide93. Mountedon guide 94 is a third spring assembly 105 which forces theother side of the film holder down against the guide .94 so that thefilm holder is in spaced parallel relationship to the plane of thetransparency and member 80.

Mounted on member 80 is an angularregistration adjusting screw 107 whichis movable into engagement with guide 94 to pivot the guide 94 and thefilm holder around pivot point 95. The strength of spring assembly 101is sufliciently high to maintain the film holder againstthe shoulder 96in the event of counter clockwise movement; of the guide 94 and filmholder 85 about pivot point 95.. Angular registration adjusting screw107 includes a pres-- sure screw 10 9 to provide automatic locking ofthe thumb) screw once a proper position has been selected.

Also mounted on member 80 is a transverse positioning screw assembly 110identical in structureto angular registration adjusting screw assembly107 which operates to position the transparency holder 85 in atransverse direction.

The transparency holder 85 includes a generally rectangular supportmember 112 which carries pins 114 which serve as locating pins for thetransparency. Referring to FIGS. 4 and 6, the rectangular transparencysupporting member 112 includes four spring-loaded clips 116 which can bemanually depresesd and rotated to unclamp the transparency which ispreferably held between two flat glass plates 117 and 118. In this way,the trans parency is properly registered in the film holder assembly andmaintained in substantially parallel relationship with respect to member80.

Referring to FIGS. 5 and 7, the guide assembly 94 is mounted for pivotalmovement around pivot 95 which includes a clamping nut 118 which locksthe guide in its final position. To permit rotational movement of theguide 94, an oblong slot 119 is provided in the guide permitting arcuateguided movement, and received in the aperture is a second locking thumbscrew 121. The second locking screw 121 in conjunction with clamping nut118 eliminates lifting of either end of guide 94.

Referring to FIGS. 8 through 10, the web position sensing assemblyof thepresent invention is shown and includes a pivotal lever arm 125 which ismounted for movement on support 71 by a bearing assembly, the details ofwhich are shown in FIG. 9. Lever arm 125 is press-fitted over a bearing127 which in turn is slipfitted over stud 129 and held relative to thestud by the screw and washer assembly 131. This construction permitseasy transposition of the lever 125 to a second or more positions forwebs of different widths, as shown in dotted lines of FIG. 8.

As shown in FIG. 10, the lever arm includes fingers 135 mounted on thefree end thereof which contacts the edge of the web during its traveland which is biased into contact with the edge of the web whenever a webis present in the station. The web position sensing assembly alsoincludes a laterally movable linkage arm 140 having attached to one endthereof a constant force spring 141 with the other end of the constantforce spring being affixed to support element 71. This spring urges thelinkage 140 toward the left as viewed in FIG. 8 and urges the lever arm125 through the bearing 142 positioned on the end of the linkage arm 140toward the left as viewed in FIG. 8 to contact the edge of the web. Thelinkage arm 140 is connected to the support member 88 by screws 144 tomove the lens an amount proportional to the movement of the web assensed through the lever and linkage assembly. Fingers 135 affixed tothe lever arm 125 travel in slots 143 (one being shown) on theprojection side of the table. The apparatus of the present inventionalso includes conventional equipment for providing a pressuredifferential to maintain the web in contact with the projection table 34as previously described. Accordingly, the edge of the web which is beingsensed by the fingers 135 is maintained flat and prevented from curling.In the absence of a web, the travel of the fingers is limited by theends of the slots 143 as shown in FIG. 10. If desired, a plate may beatfixed to the projection table in registry with the portions of thetable between the slots to engage the edge of the web and maintain it inclose proximity to the table to prevent edge curling away from the tableand the sensing fingers 135.

The pivot point of lever 125 preferably lies in the same plane as thetransparency while bearing 142 lies essentially in the same plane as theplane of the center of the lens 90 which in turn is in parallel spacedrelation to the transparency and the projection table. The ratio of thatportion of the lever arm between the plane of the image projection tableand the plane of the center of lens 90 to the portion of the lever armbetween the plane of the transparency and the plane of the center oflens 90 is substantially identical to the magnification ratio.Therefore, any pivotal movement of arm 125 as a result of slight lateralshifting of the web will bring about a proportional movement of the lens90 in a plane which remains substantially parallel to the plane of thetransparency. Flexure plates 86a, 12, c, and d, tend to maintain member88 in a normal position, and movement of member 88 from that position isin effect op posed by the plates. The movement of the member 88 aboutthe fixed ends of flexure plates 86a, b, c and d as a result of movementof arm is relatively small therefore vertical movement of member 88toward or away from the transparency is relatively small and isnegligible. Such movement has little, if any, effect upon magnificationor focus of the projected image. Once the projected image is properlyaligned angularly, transversely and with the proper magnification andfocus, the web position sensing assembly previously described operatesin effect to shift the image with the shifting movement of the web so asto maintain the web and image in lateral registry. Each projectionassembly in each station is substantially the same as the assemblypreviously described. In this way, the transparency in each station,once oriented properly with respect to that station is maintained inthat registered position notwithstanding small lateral movements of theweb at the projection table in each station.

Further, the web contacting fingers and the projected image in eachstation are located in the same longitudinal relationship to each otherso that a given point on the edge of the web is at the sensing finger ineach unit at the moment the flash exposure occurs.

In operation, transparencies are prepared with each representative ofone color of the multi-color image. The individual transparencies arethereafter provided with registration holes for alignment of thetransparencies in the film holder 112. The transparency is assembledbetween two glass plates with the emulsion side facing the projectiontable, and the assembled glass plates and transparencies are positionedwithin the film holder and locked therein by the spring biased latchingelements 116. The films are each provided with a hole and a slot. Thehole closely fits one pin 114, while the slot fits opposed parts of theother pin 114. The slot extends parallel to a line between the pins. Inthis way, any buckling of the film due to expansion as a result ofincreases in the ambient temperature is substantially eliminated.

Transparency holder 112 with the transparency properly mounted andoriented thereon is inserted to ride on guide 93 with the opposite edgethereof being received by the shoulder 96 of guide 94. A modeling lightis activated as described in application Serial No. 240,253, filedNovember 27, 196-2 and assigned to the same assignee, and an image isprojected to the projection table. The projected image is focused byturning lens housing 89 until a sharp well-defined image is obtained. Bymanipulating the micrometer thumb screw and the angular registryadjustment knob 107 and the transverse adjustment knob 110, themagnified and focused image is brought into proper register in the imageplane.

The details of the registration sequence are as follows: Focus has beenaccomplished by manipulation of the lens housing 89, angular alignmentis accomplished by manipulation of the knurled thumb screw 107 to effectangular registration of the projected image. Next, some transverseadjustment may be made by the transverse position assembly 110 whicheffects transverse shifting of the projected image. At this point anevaluation of registration is made and in most instances magnificationof the image may be slightly different from that desired. Compensationmay be made by adjusting the micro-meter knob 67.

Once the focus and magnification have been established, relativelylittle further adjust-ment of these two items is required from onetransparency to the next transparency in a given station, provided thetransparencies are of reasonably the same qualiy. For example, inrunning one composite color image from five color transparencies, andthereafter nunning another composite image from a second set oftransparencies it is usually not necessary to make substantial changesin magnification and focus after the initial adjustment for the firstset has been made. Assuming the sets of transparencies are of similarquality, little further adjustment of focus and magnification isrequired by the user.

A11 rolls are arranged with the respective axis of each roll in parallelrelationship with the axis of the remaining rolls, and thus the webduring its travel through the machine and through the pinch rollsremains relatively close to a mean position and does not Wandersubstantially. Any slight transverse movement of the web withoutcorrection would tend to bring about transverse misregistry of theimages in each station. By providing an automatic transverse webposition sensing assembly which maintains the projected imagetransversely registered with respect to the web and the previous image,as described, and by providing an index mark for all subsequent flashexposures, at the time that the flash tube fires to expose the web instations 1221 through e, the previously developed image and theprojected image of that particular station are maintained in propertransverse and longitudinal registry. Stations 12b through He areprovided with a longitudinally adjustable photo pick-up device of thetype described in application Serial No. 240,253 previously mentioned,to provide accurate longitudinal registration with respect to the indexmark. The adjustment of the photo pick-up device is the last adjustmentrequired for registration. At this point, the machine has been properlyadjusted with respect to focus, magnification, transverse, angular andlongitudinal registry.

One feature of the present invention is movement of lens 90 relative tothe transparency such that the lens moves without appreciably changingthe magnification and focus. Since a relatively small lateral movementof the lens is required in proportion to the lateral movement of theweb, the change of distance between the lens and the transparency isrelatively small. The same effect may be achieved by moving any elementprojection system which effects lateral movement of the projected image.

While the forms of apparatus herein described constitute preferredembodiments of the invention, it is to be understood that the inventionis not limited to these precise forms of apparatus, and that changes maybe made therein without departing from the scope of the invention whichis defined in the appended claims.

What is claimed is:

1. Apparatus for projecting an image on a movable electrophotographicweb travelling in a predetermined path comprising:

means defining a projected image plane,

means to maintain the web relatively fiat in said image plane,

means spaced from said image plane for projecting onto the web a lightimage of predetermined fixed width relative to the web,

said projection means including means to mount an original in spacedrelation to said image plane, means to sense lateral deviation of theweb from said predetermined path, and

means cooperating with said sensing means to effect lateral movement ofsaid projected image in the same direction and in an amount equal tosaid lateral deviation of the web whereby the projected image ismaintained in lateral registry on the web.

2. Apparatus for projecting an image on a movable electrophotographicweb travelling in a predetermined path comprising:

means defining a projected image plane,

means to maintain the web relatively flat in said image plane,

means spaced from said image plane for projecting onto the web a lightimage of predetermined fixed width relative to the web, said projectionmeans including means to mount an original in spaced relation to saidimage plane,

means contacting the side edge of the web to sense lateral deviationthereof from said predetermined path, and

means cooperating with said sensing means to effect lateral movement ofsaid projected image in the same electrophotographic web travelling in apredetermined path comprising:

means defining a projected image plane,

means to maintain the web relatively flat in said image plane,

means spaced from said image plane for projecting onto the web a lightimage of predetermined fixed Width relative to the web,

said projection means including means to mount an original in spacedrelation to said image plane,

means to sense lateral deviation of the web from said predeterminedpath,

said sensing means including pivotally mounted arm means,

means on said pivotally mounted arm contacting the side edge of the web,and

means cooperating wit-h said sensing means to effect lateral movement ofsaid projected image in the same direction and in an amount equal tosaid lateral deviation of the web whereby the projected image ismaintained in lateral registry on the web.

4. Apparatus for projecting an image on a movable electrophotographicweb travelling in a predetermined path comprising:

means defining a projected image plane,

means to maintain the web relatively flat in said image plane,

means spaced from said image plane for projecting onto the Web a lightimage of predetermined fixed width relative to the web,

said projection means including means to hold an original in spacedrelation to said image plane,

lens means mounted between said original holding means and said imageplane,

means to sense lateral deviation of the Web from said predeterminedpath, and

means cooperating with said sensing means to effect lateral movement ofsaid lens in proportion to said lateral deviation of the web whereby theprojected image is maintained in lateral registry on the web.

5. Apparatus for projecting 'an image on a movable electrophotographicweb travelling in a predetermined path comprising:

means defining a projected image plane,

means to maintain that portion of the web being exposed in said imageplane in a relatively fiat condition,

means spaced from said image plane for projecting onto the web a lightimage of predetermined fixed width relative to the web.

said projection means including means to hold an original in spacedrelation to said image plane,

means to effect lateral and angular orientation of the projected imagewith respect to said image plane,

means to sense lateral deviation of the web from said predeterminedpath, and

means cooperating with said sensing means to effect lateral movement ofsaid projected image in the same direction and in an amount equal tosaid lateral deviation of the web whereby the projected image ismaintained in lateral registry on the web.

6. Apparatus for projecting an image on a movable electrophotographicweb travelling in 'a predetermined path comprising:

means defining a projected image plane,

means to maintain that portion of the web being exposed in said imageplane in a relatively flat condition,

means spaced from said image plane for projecting onto the web a lightimage of predetermined fixed width relative to the web,

means to move said projection means relative to said image plane forvarying the size of the projected image,

said projection means including means to hold an original in spacedrelation to said image plane,

lens means mounted between said original holding means and said imageplane and including means to focus said projected image,

said means to hold said original including means to effect lateral andangular orientation of the original with respect to said image plane,

means contacting the edge of the web to sense lateral deviation of theWeb from said predetermined path, and

means cooperating with said sensing means to effect lateral movement ofsaid lens means in proportion to said lateral deviation of the web Whilesubstantially maintaining focus and magnification of the projected imagewhereby the projected image is maintained in lateral registry on theweb:

7. An electrophotographic apparatus for forming an enlarged image on amovable electrophotographic web travelling in a predetermined pathcomprising:

means defining a projected image plane,

means to maintain the web relatively flat in said image plane,

means spaced from said image plane for projecting onto the web a lightimage of predetermined fixed width relative to the web,

said projection means including a projection table, lens means and flashmeans to expose the web to an original to be reproduced,

means included in said projection means for mounting an original betweensaid flash means and said lens means,

means to effect alignment of the projected image with a side edge of theweb,

means mounting said lens means for movement relative to said originaland laterally relative to the Web path,

means to sense lateral deviation of an edge of the web from saidpredetermined path,

said sensing means including a pivotally mounted arm,

linkage means positioned to effect movement of the lens in the samedirection as the web in response to movement of said arm, and

the ratio of the portion of the arm between the portion thereofcontacting the web and the center of the lens to that portion betweenthe center of the lens to the plane of the original being substantiallythe same as the magnification ratio of said lens.

8. Apparatus for projecting an image on a movable electrophotographicweb travelling in a predetermined path comprising:

means defining a projected image plane,

means to support the portion of the Web being exposed substantially flatin said image plane,

means spaced from said Web support means for projecting onto the web alight image of predetermined fixed width relative to the web,

means cooperating with said projection means to effect focus andmagnification of the projected image,

said projection means including means to support an original inpredetermined angular and lateral registry with respect to the web insaid image plane,

said original supporting means including means defining a supportingsurface in a substantially flat parallel spaced relation to said imageplane,

first means on said supporting surface to maintain an original insubstantially flat parallel relation thereto,

second means cooperating with said supporting surface to effect lateraland angular movement of said first means whereby the said predeterminedlateral and angular registry is achieved,

lens means mounted between said original supporting means and said websupport means,

means to sense lateral deviation of the web from said predeterminedpath, and

means cooperating with said sensing means to effect lateral movement ofsaid projected image in the same direction and in an amount equaltolateral deviation of the web whereby the projected image is maintainedin lateral registry on the web.

9. Apparatus for projecting an image on a movable electrophotographicweb travelling in a predetermined path comprising:

means defining a projected image plane,

means to support the portion of the web being exposed substantially flatin said image plane,

means spaced from said web support means for projecting onto the web alight image of predetermined fixed width relative to the Web,

1 means toetfect focus and magnification of the projected image,

said projection means including means to support an original inpredetermined angular and lateral registry with respect to the web insaid image plane,

said original supporting means including means defining a supportingsurface in substantially fiat parallel spaced relation to said imageplane,

first means on said supporting surface to maintain an original insubstantially fiat parallel relationship thereto,

second means cooperating with said supporting surface to effect lateraland angular movement of said first means whereby the said predeterminedlateral and angular registry is achieved,

lens means positioned between said original supporting means and saidweb support means,

means to sense lateral deviation of the Web from said predeterminedpath,

said sensing means including a pivotally mounted arm,

the pivot point of said arm being in substantially the same plane as theplane of the original,

linkage means positioned effectively in the same plane as said lensmeans to effect movement of said projected image with respect tomovement of said arm, and

the ratio of the portion of the arm between the image plane and thecenter of said lens to that portion between the center of the lens tothe plane of the original being substantially the same as themagnification ratio of said lens.

10. Apparatus as set forth in claim 9 wherein said projection meansinclude flexure plate means mounted on said first means for supportingsaid lens means in spaced relation to the original holding means.

11. An electrophotographic apparatus for forming a plurality of image-son a movable electrophotographic web travelling in a predetermined pathcomprising:

a plurality of stations, each station including means to charge, exposeand develop a portion of the Web, means in each station defining aprojected image plane, said exposing means of each station includingmeans spaced from the corresponding image plane to pro ject an imagethereon, means in each station to maintain that portion of the web beingexposed relatively flat in said image plane, means in the first of saidstations to form an index mark,

means in said stations other than said first to sense said index markfor controlling the exposure means in said other stations,

means in each station to sense deviation of an edge of the Web from saidpredetermined path,

said deviation sensing means and the projected image in each saidstation being in the same longitudinal relation to each other so thatthe same point on the edge of the Web is being sensed during exposurethereof in each station,

and means in each said station cooperating with said corresponding websensing means to move the projected image in said station an amountproportional to the deviation of the edge of the web to maintain theprojected image in each said station in lateral relationship with theimage formed in the preceding station.

12. An electrophotographic apparatus for forming a plurality of imageson a movable electrophotographic web travelling in a predetermined pathcomprising:

a plurality of stations, each station including means to charge, exposeand develop a portion of the web, means in the first of said stations toform an index mark,

means in said stations other than said first to sense said index markfor controlling the exposure means in the other stations,

means in each station defining a projected image plane,

said exposing means of each station including means spaced from thecorresponding image plane to project an image thereon,

means in each station to maintain the portion of the web being exposedrelatively flat in said image plane,

means in each said station to sense deviation of the web from saidpredetermined path, and

means in each station cooperating with each said web sensing means toeflect lateral movement of the projected image in said station inproportion to the lateral deviation of the web in said station wherebythe projected images are maintained in lateral registry on the webduring travel thereof through each said station,

1 3. An electrophotographic apparatus for forming a plurality of imageson a movable electrophotographic web travelling in a predetermined pathcomprising:

a plurality of stations, each station including means to charge, exposeand develop a portion of the web, means in the first of said stations toform an index mark, means in said stations other than said first tosense said index mark for controlling the exposure means in the otherstations,

means in each said station defining an image plane,

each exposure means in each said station including flash means to exposethe web to an image to be reproduced,

means in each station to maintain the portion of the 'Web being exposedrelatively flat in said image plane,

means toeffec-t magnification and focus of the original,

means in each said exposure station for holding an original,

said means to hold said original including means to effect lateral andangular orientation of the projected image of said original with respectto the web in said image plane,

means in each said station to sense deviation of an edge of the Web fromsaid predetermined path, and

said sensing means in each said station cooperating with thecorresponding exposure means to effect lateral movement of the projectedimage in said station in proportion to the lateral deviation of the webin said station while substantially maintaining magnification and focusof the projected image whereby the projected images are maintained inlateral registry on the web during travel there-of through each saidstation.

14. An electrophotognaphic apparatus for forming a plurality of imageson an electroplrotographic web comprising:

a plurality of stations, each station including charger means, exposuremeans and developing means,

means in each station defining an image plane,

means in each station to support the portion of the web being exposedsubstantially flat in said image plane,

means defining a predetermined path of advancement for the web throughsaid stations,

said exposure means of each station including projection means andprojection table means spaced therefrom,

said projection tables being in generally the same plane,

means cooperating with said projection means of each station to effectfocus and magnification of the projected image,

said projection means of each station including means to support anoriginal in predetermined angular and lateral registry with respect tosaid image plane,

lens means mounted between said original supporting means and saidprojection table means of each station,

said original supporting means of each station including means defininga supporting surface in substantially flat parallel spaced relation tosaid image plane,

first means on said supporting surfiace of each station to maintain anoriginal in substantially flat parallel relation thereto,

second means cooperating with said supporting surface of each station toeffect lateral and angular movement of said first means whereby the saidpredetermined lateral and angular registry is achieved,

means in each said station to sense lateral deviation of the web fromsaid predetermined path,

said sensing means including a pivotally mounted arm, the pivot point ofsaid arm being in substantially the same plane as the plane of theoriginal in the corresponding station,

linkage means in each station positioned effectively in the same planeas said corresponding lens means to effect movement of said lens meansin response to movement of said arm,

the ratio of the portion of the arm between the image plane and centerof the lens to that portion between the center of the lens to the planeof the original being substantially the same as the magnification ratioof said lens,

developing means being positioned between the projection means of eachstation and including developer roll means for treating the web with aliquid developer,

guide roll means between the developing means of a preceding station andthe projection table means of a succeeding station contacting thedeveloped surface of the web,

means cooperating with said guide roll means for substantially reducingoff-setting and mechanical transfer of liquid developer from thedeveloped web,

means cooperating with said projection means of the first station tocontrol the frequency of exposures for a given period of time wherebythe length of web between a series of successive images is maintainedrelatively small,

means in the first station to form an index mark controlling theexposure means in subsequent stations,

means in each subsequent station for sensing the index mark andactuating said projection means,

means to sever said web following development of the last image thereon,and

means cooperating with said frequency control means to sever said webbetween successive images.

References Cited by the Examiner UNITED STATES PATENTS JOHN M. HO'RAN,Primary Examiner.

1. APPARATUS FOR PROJECTING AN IMAGE ON A MOVABLE ELECTROPHOTOGRAPHICWEB TRAVELLING IN A PREDETERMINED PATH COMPRISING: MEANS DEFINING APROJECTED IMAGE PLANE, MEANS TO MAINTAIN THE WEB RELATIVELY FLAT IN SAIDIMAGE PLANE, MEANS SPACED FROM SAID IMAGE PLANE FOR PROJECTING ONTO THEWEB A LIGHT IMAGE OF PREDETERMINED FIXED WIDTH RELATIVE TO THE WEB, SAIDPROJECTION MEANS INCLUDING MEANS TO MOUNT AN ORIGINAL IN SPACED RELATIONTO SAID IMAGE PLANE, MEANS TO SENSE LATERAL DEVIATION OF THE WEB FROMSAID PREDETERMINED PATH, AND MEANS COOPERATING WITH SAID SENSING MEANSTO EFFECT LATERAL MOVEMENT OF SAID PROJECTED IMAGE IN THE SAME DIRECTIONAND IN AN AMOUNT EQUAL TO SAID LATERAL DDVIATION OF THE WEB WHEREBY THEPROJECTED IMAGE IS MAINTAINED IN LATERAL REGISTRY ON THE WEB.